Recently, a screen is shared between a remote terminal operated by a worker and an instruction terminal operated by an instructor by using public line network, such as Internet network. In such a screen sharing, a remote terminal and an instruction terminal share a screen displaying an image taken by a worker, and an instructor inputs a work instruction for the image shared on the screen to provide an appropriate work instruction to the worker on the remote terminal.
For instance, Patent Document 1 discloses that an instructor inputs a work instruction to the instruction terminal and a worker recognizes the work instruction through the trajectory etc. of the work instruction.